# print(1+2-3)
# print(1+2*3)
# print(1+2/3)
# #变量
# avg = (67.5 + 89.0 + 12.9 + 32.2) / 4
# #python中**2表示乘2次方运算，**3为乘3次方
# total = (67.5 - avg) ** 2 + (89.0 - avg) ** 2 + (12.9 - avg) ** 2 + (32.2 - avg)** 2
# result = total / 3
# print("result=",result)
# #类型
# a=1
# print(type(a))
# a = 0.5
# print(type(a))
# a = 'hello'
# print(type(a))

# #求字符串长度
# a = 'hello'
# print(len(a))
# #字符串拼接
# a = 'hello'
# b = 'world'
# print(a + b)
# #多类型输出
# num = 10
# print(f'num = {num}')
#浮点数并不精准的证明
# print(0.1)
# print(0.2)
# print(0.3)
# print(0.1 + 0.2)